import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        // 注意 hasNext 和 hasNextLine 的区别
        long n = in.nextInt();
        long a = (long) Math.sqrt(n);
        long x1 = a * a,x2 = (a + 1)*(a + 1);
        if(n - x1 < x2 - n) System.out.println(x1);
        else System.out.println(x2);
    }
}